You can give a suggested start time on the smart settings, but you can’t tell it when it needs to start. To give it a suggested start time, go to the programs page and then tap “smart Watering”. You’ll see the suggested start time setting there.
This does not mean it will start at that time, but it will take that into consideration. From what I’ve seen in my testing, it usually sets it around 15 minutes +/- the time you’ve input.